Circuit interrupter having an improved insulating support structure

ABSTRACT

A circuit interrupter, such as a circuit breaker comprising an electrically insulating base or support member on which is supported a stationary contact assembly and a pivotally mounted switch or contact arm having movable contact means thereon adapted to engage the stationary contact assembly along with a pair of associated spaced terminal members.

United States Patent inventor Fred Bould Pittsburgh, Pa. Appl, No. 770,149 Filed Oct. 24, 1968 Patented June 8, 1971 Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

CIRCUIT INTERRUPTER HAVING AN IMPROVED INSULATING SUPPORT STRUCTURE 9 Claims, 4 Drawing Figs.

US. Cl 200/146, 200/168 Int. Cl ..1I01h 33/12 Field ofSearch 200/146, 168 A References Cited UNITED STATES PATENTS 1/1963 Baird 200/168(A) l2/l964 Bury 200/168(A) l [/1965 Goodwin, .lr. 200/146 11/1966 Cellerini et al. 200/l68(A) 1/1 967 Wilson 200/l46X 9/l 968 Bould 200/ 146 Primary Examiner-Robert S. Macon Attorneys-A. T. Stratton and Clement L. McI-Iale ABSTRACT: A circuit interrupter, such as a circuit breaker comprising an electrically insulating base or support member on which is supported a stationary contact assembly and a pivotally mounted switch or contact arm having movable contact means thereon adapted to engage the stationary contact assembly along with a pair of associated spaced terminal members. 1

PATENTEDJUN 8L9?! 3584-0170- SHEET 1 or 2 INVENTOR Fred Bould My. av /4.2m

ATTORNEY CIRCUIT INTERRUPTER IIAVING AN IMPROVED INSULATING SUPPORT STRUCTURE CROSS-REFERENCES TO RELATED APPLICATIONS Certain inventions disclosed in thepresent application are disclosed and claimed in copending application concurrently with this application by F. Bould and R. Hauser and in copending application Ser. No. 538,996 filed Mar. 31, I966 by J. D. Findley which are both assigned to the same assignee as the present application.

BACKGROUND OF THE INVENTION This invention relates to circuit interrupters, such as circuit breakers, and more particularly to electrically insulating support structures which form part of such interrupters. In certain types of circuit interrupters or circuit breakers, a relatively stationary contact assembly having first terminal means associated therewith is supported on an electrically insulating support member. A switch or contact arm having movable contact means thereon is pivotally supported on the same insulating support member and is movable to actuate the movable contact means into engagement with corresponding contact means which form part of the stationary contact assembly. A second terminal means is associated with the movable switch or contact arm of such an interrupter and is also supported on the insulating support member. A known structure of this type is illustrated in U.S. Pat. No. 2,836,684 which issued May 27, I958 to H. .I. Lingal et al. and which is as-' the overall circuit interrupter, particularly when one or more current transformers are mounted on the circuit breaker.

SUMMARY OF THE INVENTION In accordance with the invention, a circuit interrupter or circuit breaker is provided in which an electrically insulating support member includes first and second generally parallel planar portions which are interconnected and offset from each other with a predetermined spacing between said planar portions. A stationary contact assembly is mounted on the first planar portion and has associated therewith a first terminal means which extends through an opening in the insulating support member and projects away from the second planar portion in a direction generally perpendicular to the first planar portion a predetermined distance from the first planar portion. A hinge support member is mounted on the second planar portion of the insulating support member to pivotally support a switch or contact arm having movable contact means thereon which may be actuated by movement of the switch arm into engagement with the relatively stationary contact means which form part of the stationary contact assembly. The hinge support member has associated therewith a second terminal means which extends through an opening in the second planar portion of the insulating support member and projects away from the second planar portion in the same direction as the first terminal means a distance which is substantially equal to the sum of the predetermined spacing between the first and second planar portions and the distance which the first terminal means projects away from the first planar portion. A current transformer may be mounted on the second terminal means of the circuit interrupter in the space or compartment which results between the second planar portion of the insulating support member and the end of the second terminal means away from said second planar portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view, partly in section, of a circuit breaker embodying the principles of the invention;

FIG. 2 is a front elevational view of an electrically insulating support member which forms part of the circuit breaker shown in FIG. 1;

FIG. 3 is a side elevational view, partly in section, of the electrically insulating support member shown in FIG. 2; and

FIG. 4 is a rear elevational view of the electrically insulating support member shown in FIGS. 2 and 3. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and FIG. 1 in particular, there is illustrated a circuit interrupter, more specifically a circuit breaker l0, embodying the principles of the invention. The circuit breaker 10 may be of the type which is disclosed in greater detail in copending application Ser. No. 770,296 filed concurrently by F. Bould, R. Hauser and J. H. Taylor which is assigned to the same assignee as the present application. The circuit breaker 10 may be of the drawout type and may be mounted on a rigid frame which includes a pair of spaced angle or cross members 320 and 330 and which supports the elements of the circuit breaker 10. The frame of the circuit breaker 10 may be provided with rollers (not shown) to facilitate moving or rolling the circuit breaker 10 into and out of an associated cubicle or cell in order to connect and disconnect the circuit breaker 10 in an electrical circuit which is to be opened and closed.

In general, the circuit breaker 10 includes an electrically insulating base or support member which is rigidly supported on the framework of the circuit breaker 10, which includes the crossmembers 32.0 and 330, along with other pole units similar to the circuit breaker 10, as disclosed in greater detail in the last-mentioned copending application. The circuit breaker 10 also includes a stationary contact assembly 20 which is rigidly supported on the insulating support member 110 and which may include portions which serve as the upper terminal of the circuit breaker 10. In addition, the circuit breaker 10 includes a movable switch or contact arm 30 having movable main and arcing contact members mounted thereon which is pivotally supported on a hinge member or pivot support member 40 which, in turn, is rigidly supported on the insulating support member 110 and which may include portions which serve as the lower terminal of the circuit breaker 10 as viewed in FIG. 1. As illustrated in FIG. 1, the circuit breaker 10 may also include a pair of spaced upper and lower disconnecting contact assemblies 60 and 62, respectively which are removably assembled on the upper and lower terminals, respectively, of the circuit breaker l0 and which are adapted to engage the upper and lower fixed electrical conductors or studs and 160, respectively, in order to electrically connect the circuit breaker 10 to the bus bars or electrical power conductors of an associated switchgear structure (not shown) which may include a cell or housing in which the circuit breaker 10 is normally disposed. Each of the disconnecting contact assemblies 60 and 62 may be of the type which is described in detail in copending application Ser. No. 538,996, previously'mentioned.

More specifically, the electrically insulating support member 110 is formed from an electrically insulating material having a relatively high structural strength, such as a glass filled polyester material by molding or casting. The insulating support member 110 includes the first and second generally planar portions 112 and 114, respectively, which are interconnected by an intermediate generally planar portion 113 which, as illustrated, is generally perpendicular to both of the associated planar portions 112 and 114. The planar portions 112 the circuit breaker 10 as will be explained hereinafter. The insulating support member 110 also includes a third generally planar portion 115 as shown in FIG. I at the upper end of the support member 110 with the plane in which the planar por-' tion 115 generally lies being disposed intermediate the planes in which the planar portions 112 and 114 generally lie. As best shown in FIGS. 2 and 4, the insulating support member 110 also includes a pair of sidewall portions 122 and 124 which are fonned integrally with the planar portions 112, 114 and 115 at the opposite sides of said planar portions and which are disposed generallyperpendicular to said planar portions. The sidewall portions 122 and 124 of the support member 110 project away from the associated planar portions 112, 114 and 115 in both directions, except at the lower end of the support member 110 as best shown in FIG. 3. In order to permit the mounting of the stationary contact assembly on the planar portion 112 of the support member 110 along with a associated upperterminal of the circuit breaker 10, the planar portion 112 includes a central opening 132, as shown in FIGS. 2 and 4. Similarly, in order to permit the mounting of the hinge member or pivot support member 40 along with an associated lower terminal of the circuit breaker 10 on the planar portion 114 of the support member 110, the planar portion 114 includes a central opening 134, as shown in FIGS. 2 and 4.

As mentioned previously, the insulating support member 110 is rigidly supported on the framework of the circuit breaker 10 which includes the upper and lower angle or crossmembers 320 and 330, respectively, as best shown in FIG. 1. In particular, the upper end of the insulating support member 110, as shown in FIGS. 1 and 2, includes a central opening 162 which is substantially aligned with an opening in the adjacent angle member 320 with a suitable fastening means, such as the bolt 322 passing through said openings to secure the support member 110 to the angle member 320. In order to increase the electrical creepage insulation between the stationary contact assembly 20 and the electrically conducting parts of the framework of the circuit breaker which includes the angle member 320, the support member 110 includes the projecting portions 125 and 126 which are disposed between the stationary contact assembly 20 and the mounting bolt 322. Similarly, the projecting portion 126A is provided on the other side of the support member 110 between the angle member 320'and the stationary contact assembly 20 to increase the electrical creepage insulation'between said angle member and saids't ationary contact assembly. A pair of electrically insulating projecting portions are also provided at the upper end of the support member 110. around the head of the bolt 322 with the curved portions 124 extending between the rib portions 123 and 125 of the support member 110, as best shown in FIG. 2. A pair of rib portions 127 and 129 are also provide at the rear of the support member 110, as best shown in FIGS. 3 and 4, to structurally reinforce the upper end of the support member 110 on the opposite sides of the bolt 322. As shown in FIG. 1, a nut 321 is disposed on the threaded end of the bolt 322 away from the head of said bolt. Similarly, a pair of spaced openings 154 and 156 are provided at the lower end of the support member 122 and substantially aligned with corresponding openings in the lower angle member 330 with a pair of suitable fastening means, such as the bolts 332, passing through the openings 154 and 156 and the corresponding openings in the angle member 330 to secure the insulating support member 110 to the lower angle member 330. A nut 331 is disposed on the threaded end of each of the bolts 332 as shown in FIG. 1. In order to provide additional electrical creepage insulation between the conducting parts of the circuit breaker l and the lower angle member 330, the support member 110 also includes a projecting portion 128, as shown in FIGS. 1 and 2, which is disposed between the conducting parts of the circuit breaker and the lower angle member 330 which is normally maintained at ground potential similarly to the other parts of the framework of the circuit breaker 10.

As described in greater detail in copending application Ser. No. 770,297 previously (WE. Case 39,951) previously mentioned, the stationary contact assembly 20, as illustrated, includes an electrically conducting intermediate support member or wall member 34 and a pair of outer support or wall members 32 (only one shown) which are also formed from electrically conducting material. As described in the copending application just mentioned, the right-hand portions of the support members 32 and 34 are disposed in tightly assembled relationship and secured or clamped together by suitable means, such as rivets. The right-hand portions of the support members 32 and 34 extend through the opening 132 in the planar portion 112 of the support member and project in a direction away from the planar portion 114 a predetermined distance away from the planar portion 112. As further described in the copending application just mentioned, the outer pair of support members 32 include left-hand portions which are offset or spaced from the intermediate support member 34 at the front side of the support member 110 and which are interconnected with the associated righthand portions of the support members 32 at the rear side of the support member 110 by the intermediate portions which are generally disposed generally transversely with respect to the intermediate support member 34, as indicated at 32A in FIG. 1 for the outer support member 32. It is important to note that the right-hand portions of the support members 32 and 34 which project to the right of the support member 110 form the upper terminal of the circuit breaker 10, as described in the lastmentioned copending application. In order to secure the stationary contact assembly 20 to the planar portion 112 of the insulating support member 110, a pair of mounting bolts 84 are provided which pass through the openings 142 and 144 in the planar portion 112 of the support member 110, as shown in FIG. 2, and engage the associated nuts 94 which are mounted on the intermediate portions 32A of the outer support members 32 of the stationary contact assembly 20. As mentioned previously, the upper disconnecting contact assembly 61) is removably assembled on the upper terminal formed by the support members 32 and 34.

The stationary contact assembly 20 also includes a plurality of main stationary contact members 72 which are pivotally supported on a pivot pin or bolt 62 which, in turn, is supported on and passes through substantially aligned openings in the support members 32 and 34. In order to transfer current between the main stationary contact member 72 and the electrically conducting support members 32 and 34, an electrically conducting bearing tube 64 is disposed on the pivot pin or bolt 62, as shown in FIG. 1. Each of the main stationary contact members 72 has mounted at the lower end thereof a main stationary contact surface or insert 72A. In order to insure adequate contact pressure between the main stationary contact members 72 and the movable main contact member, as will be described hereinafter, a plurality of compression springs 77 is disposed between the backs of the contact members 72 and the intermediate portions 32A of the outer support members 32. The right ends of the spring 77 may be retained in position by associated spring seat members 75 which are disposed between the springs 77 and the intermediate portions 32A of the support members 32. A pair of spring guide members 74 may be disposed on opposite sides of the intermediate support member 34 to assist in maintaining the plurality of compression springs 77 in proper operating positions with the right ends of the spring guides 74 projecting through aligned openings provided in the spring seat members 75 and the intermediate portions 32A of the support members 32 into a pair of recesses 152 and 154 provided in the support member 1 10, as shown in FIG. 2. The front ends of the spring guide members 74 includes slots which bear against the bearing tube 64 which is disposed on the pivot pin or bolt 62. Since the compression springs 77 bias the contact members 72 in a clockwise direction about the pivot pin 62, a stop member 66 is mounted on the support members 32 and 34 to limit the clockwise rotation of the contact member 72 under the influence of the compression springs 77.

The stationary contact assembly also includes a pair of laterally spaced arcing contact members, as indicated at 62 in FIG. 1, which are supported on a support pin 52 which, in turn, is mounted on the support members 32 and 34, as explained in the copending application last mentioned. Each of the arcing contact members 62 includes an arcing contact surface or insert 64, as shown in FIG. 1. The arcing contact members are biased toward the intermediate support member 34 and toward one another by a pair of compression springs, as indicated at 53 in FIG. 1, which are disposed on the support pin 52 on opposite sides of said arcing contact members. In order to guide the separating or approaching movements of the arcing contact members 62 during operation of the circuit breaker 10, a guide pin 54 is mounted adjacent the rear ends of the arcing contact members 62, each of which includes a slot to permit the movement of the arcing contact members 62 during the operation of the circuit breaker 10.

In order to pivotally support the switch or contact arm at a location which is vertically spaced from the stationary contact assembly 20 just described, the pivot support or hinge member 40 is rigidly secured to the planar portion 114 of the insulating support member 110. As best shown in FIG. I, the hinge member 40 includes a pair of support members 42 which are formed from a material having a relatively high electrical conductivity such as silver plated copper. The righthand portions of the support members 42 are disposed in tightly assembled relationship and secured or clamped together by suitable means, such as rivets, to form the lower terminal of the circuit breaker 10 on which the lower disconnecting contact assembly 62 is assembled, as shown in FIG. I. The right-hand portions of the support members 42 extend through the opening 134 in the planar portion 114 of the support member 110 and project to the right from the planar portion 1 14 in the same direction as the support members 32 and 34 which make up the upper terminal of the circuit breaker 10. The right-hand portions of the support members 42 which form the lower terminal of the circuit breaker 10 project away from the associated planar portion 114 of the support member 110 a predetermined distance which is substantially equal to the sum of the predetermined spacing between the planar portions 112 and 114 and the distance that the upper terminal of the circuit breaker 10 which includes the right-hand portions of the support members 32 and 34 projects away from the associated planar portion 112 in order that the ends of the upper and lower terminals of the circuit breaker 10 on which the upper and lower disconnecting contact assemblies 60 and 62, respectively, are disposed will be substantially vertically aligned. The left-hand portions of the support members 42 which project to the left of the support member 110 are generally parallel to' the associated right-hand portions and are offset from the associated right-hand portions in opposite directions with the left-hand portions of the support members 42 being laterally spaced from one another and interconnected to the associated right-hand portions of the support members 42 which are disposed at the rear of the support member 110 by the intermediate portions which are disposed generally transversely or perpendicular with respect to the associated left and right-hand portions of the support members 42. The intermediate portions of the support members 42 are assembled to bear against the associated planar portion 114 of the support member 110.

In order to rigidly secure the support or hinge member 40 to the planar portion 114 of the support member 110, the intermediate portions of the support members 42 include openings in which are secured parts of suitable fastening means, such as the nut 96 indicated in FIG. 1, which are rigidly secured in the associated openings by suitable means, such as press fitting. When the hinge member 40 is mounted on the planar portion 114 of the support member 110, a pair of bolts 86 as shown in FIG. 1 are assembled through a pair of associated openings 146 and 148 in the planar portion 114, as shown in FIGS. 2 and 4, and through the associated openings in the inter mediate portions of the support members 42 to engage the nuts 96. The bolts 86 are then tightened until the intermediate portions of the support members 42 bear against the planar portion 1 l4 ofthe support member 110, as shown in FIG. 1.

In order to pivotally support the switch or contact arm 30 on the hinge member 40, a pivot bolt or pin 228 is provided which passes through substantially aligned openings in the left-hand or hinge portions of the support members 42 and extends across the space between the left-hand portions of the support members 42. The pivot bolt 228 may be retained in assembled relation with the hinge member 40 by suitable means, such as the nut 229, which is disposed on the threaded end of the pivot bolt 228 at the end of said bolt away from the head thereof.

As described in greater detail in copending application Ser. No. 770,297 previously mentioned, the switch or contact arm 30 includes one or a pair of generally U-shaped contact support members, as indicated at 224 in FIG. 1, which are pivotally supported on the pivot bolt 228. The contact support members 224 are formed from a material having a relatively high electrical conductivity. In order to assure adequate contact pressure between the arms of the support members 224 and the associated left-hand portions of the support members 42, a pair of spring washers 232 may be disposed on the pivot bolt 228.

The movable main contact member or block 250 as shown in FIG. 1 is mounted or supported on the portions of the support members 224 away from the pivot bolt 228 and is disposed to move in a generally arcuate path about the axis of the bolt 228 when the support members 224 are actuated for rotation about the axis of the bolt 228. The movable main contact member 250 is formed from a material having a relatively high electrical conductivity such as silver plated copper and includes a main contact surface or insert 252 which is formed from a material having greater wearing ability than the material from which the main contact member 250 is formed. It is to be noted that the main contact member 250 extends substantially across the width of the switch or contact arm 30 along with the main contact surface 252 which is disposed to engage the corresponding stationary main contact surfaces 72A on the stationary main contact members 72 which form part of the stationary contact assembly 20 previously described in a butt-type contact arrangement when the circuit breaker 10 is closed, as shown in FIG. 1.

The switch or contact arm 30 also includes a pair of arcing contact members 262 which are mounted on top of the movable main contact member 250 and supported on the same portions of the support members 224 with the arcing contact members 262 extending or projecting radially away from the axis defined by the bolt 228. The movable arcing contact members 262 are generally L-shaped in configuration and are formed from a material having a relatively high electrical conductivity, such as copper. The movable arcing contact members 262 include foot portions which are secured to the portions of the support members 224 away from the bolt 228 along with the movable main contact member 250 by a pair of bolts 222 which pass through substantially aligned openings in the foot portions of the arcing contact members 262, the movable main contact member 250 and the adjacent portions of the support members 224 to engage the nuts 223 which are rigidly secured in corresponding openings provided in the support members 224. A pair of arcing contact surfaces or inserts 264 are mounted on the upper portions of the movable arcing contact members 262, as indicated in FIG. 1. When the circuit breaker 10 is in the closed circuit condition shown in FIG. 1, the arcing contact members 262 on the switch arm 30 are disposed between the stationary arcing contact members 62 with the arcing contact surfaces 264 on the movable arcing contact members 262 engaging or bearing against the stationary arcing contact surfaces 64 on the stationary arcing contact members 62. It is to be noted that the uppermost portions of the movable arcing contact members 262, as well as the upper portions of the stationary arcing contact members 62, are formed as are runners which assist in promoting or actuating the movement of the arc which results during an opening operation of the circuit breaker 10 into an associated arc extinguishing means (not shown), such as disclosed in detail in my copending application Ser. No. 800,106 filed Feb. 18, 1969 which is assigned to the same assignee as the present application.

In order to actuate the movement of the switch or contact arm 30 between a first position. which corresponds to the closed circuit condition of the circuit breaker, as shown in solid lines in FIG. 1, and a second position which corresponds to the open circuit condition of the circuit breaker 10, as indicated in phantom at 30' in FIG. 1, the movable switch or contact arm 30 is operatively connected by means of an insulating operating member 300 which is pivotally connected at one end to a crossmember 310 which extends transversely between the arms of the support members 224 through substantially aligned openings in the support members 224 to a suitable operating mechanism which may be of the type disclosed in detail in copending application Serial No. 770,296 previously mentioned. 7

Where desired, a current transformer as indicated diagrammatically at 400 in FIG. 1, may be disposed on the lower terminal of the circuit breaker 10 which is formed by the support members 42 and previously described in the space or compartment, as indicated at 150 in H0. 3, which results below the planar portion 112 of the support member 110 and behind the associated planar portion 114. It is to be noted that the compartment 150 which results because of the configuration of the support member 110 with the spacing between the offset planar portions 112 and 114 is also partially enclosed by the sidewall portions 122 and 124 of the support member 110, as indicated in FIGS. 1 and 3. In order to insure adequate spacing or clearance between the bolts 86 and the current transformer 400 when the current transformer 400 is assembled on the lower terminal of the circuit breaker 10, the insulating support 110 includes a pair of projecting portions 172 and 174 which are located on opposite sides of the bolts 86 and which extend transversely across the back of the support member 110 between the sidewall portions 122 and 124, as shown in FIG. 4. When the current transformer is assembled on the lower terminal of the circuit breaker 10, one side of the current transformer 400 rests or bears against the projecting portions 172 and 174, as shown in FlG. l, and the lower disconnecting contact assembly 62 assists in retaining the current transformer 400 in assembled relation on the lower terminal of the circuit breaker 10, as shown in F IG. 1. in order to provide additional electrical creepage insulation between the upper terminal of the circuit breaker 10, which is formed by the support members 32 and 34, the support member 110 also includes the projecting portion 113A at the rear of the support member 110 which is disposed between the current transformer 400 and the upper terminal of the circuit breaker 10.

In the operation of the circuit breaker 10, when the switch or contact arm 30 is actuated from the closed position shown in FIG. 1 to the open position which is,indicated in phantom at 30 in FIG. 1 by the operating mechanism which is operatively connected to the switch or contact arm 30 through the insulating operating member 300, the switch or contact arm 30 is actuated to rotate about the axis defined by the bolt 228 in a generally counterclockwise direction about said axis. During the initial rotational travel of the switch arm 30, the movable arcing contact surfaces 264 will remain in engagement with the associated stationary arcing contact surfaces 64 on the stationary arcing contact members 62. During the initial rotational travel of the switch arm 30, the movable main contact surfaces 252 will also remain in engagement with the main stationary contact surfaces 72A on the contact member 72 since each of the main stationary contact members 72 will follow the movement of the switch arm 30 for a relatively short distance under the influence of the compression springs 77 in a clockwise direction about the pivot bolt 62 until the back edge of the recess provided in-each of the contact members 72 engages the common stop member 66. when the contact members 72 engage the stop member 83 during an opening operation of the circuit breaker 10, the movable main contact surface 252 will separate from the stationarymain contact surfaces 72A and an insulating gap will quickly develop between the corresponding movable and stationary main contact surfaces 252 and 72A, respectively. Meanwhile, the movable arcing contact surfaces 274 will temporarily remain in engagement with the associated stationary arcing contact surfaces 64 to maintain a current carrying path which extends from the upper terminal of the circuit breaker 10 formed by the support members 32 and 34 through the arcing contact members 62, the movable arcing contact members 262, the movable main contact member 250, and the contact support members 224 of the switch arm 30 to the left-hand portions of the support members 42 which then carry the current to the lower terminal formed by the support members 42. As the switch arm 30 continues to rotate in a counterclockwise direction about the axis defined by the pivot bolt 228, the movable arcing contact surfaces 264 will finally separate from the associated stationary arcing contact surfaces 64 and the are which results will move into an associated arc extinguishing structure where the arc will be finally extinguished or interrupted during an opening operation of the circuit breaker 10.

During a closing operation of the circuit breaker 10, the switch arm 30 will initially be in the open circuit position indicated in phantom at 30' in FIG. 1 and the position of each of the main stationary contact members 72 will be determined by the stop member 66 which engages each of the contact members 72 which are actuated in a clockwise direction about the pivot bolt 62 under the influence of the compression spring 77. As the switch arm 30 is actuated from the open circuit position shown in phantom at 30' in FIG. 1 by the operating mechanism of the circuit breaker 10 through the insulating operating member 300, the switch arm 30 will rotate in a clockwise direction from the open circuit position about the pivot bolt 228. During the final portion of the rotational travel of the switch arm 30 during a closing operation, the movable arcing contact surfaces 264 will first engage the corresponding stationary arcing contact surfaces 64 to establish a current carrying path between the upper and lower terminals of the circuit breaker 10 through the various parts previously described in connection with an opening operation prior to the time that the movable main contact member 250 and the movable main contact surface 252 thereon engages the stationary main contact surfaces 72A on the main stationary contact members 72. As the switch arm 30 is rotated further in a clockwise direction after the movable arcing contact surfaces 264 first engage the associated stationary arcing contact surfaces 64, the stationary arcing contact members 62 will be wedged or pushed farther apart than the spacing which results when the circuit breaker 10 is in the open circuit condition with the stationary arcing contact members being pushed farther apart against the forces exerted on the stationary arcing contact members by the associated biasing springs 53 until the movable arcing contact members 262 are disposed between the stationary arcing contact members 62. Any initial arcing which takes place at the separable contacts of the circuit breaker 10 will therefore take place between the movable arcing contact surfaces 264 and the corresponding stationary arcing contact surfaces 64 which are mounted on the stationary arcing contact members 62 to avoid any pitting or wearing of the movable and stationary main contact members of the circuit breaker 10. Subsequent to the establishment of the current carrying path between the arcing contact members of the circuit breaker 10 as just described, the movable main contact surface 252 on the movable main contact member 250 will engage the plurality of stationary main contact surfaces 72A on the main contact member 72 in a butt-type contact arrangement. During the final portion of the rotational travel of the switch arm 30 during a closing operation of the circuit breaker 10, the main contact members 72 of the stationary contact assembly 20 will be actuated in a counterclockwise direction about the axis of the pivot bolt 62 against the biasing forces exerted on the contact members 72 by the associated compression springs 77 until the contact members 72 reach the closed circuit positions shown in FIG. 1.

it is to be understood that the number of main stationary contact members or fingers 72 which are provided in a particular application may vary in accordance with the required current rating of the circuit breaker 10. It is also to be understood that in a particular application the relative size of the upper planar portion 112 may be increased to accommodate additional stationary contact assemblies similar to the stationary contact assembly 20 which was previously described in detail. The predetermined spacing between the offset planar portions 112 and 114 of the support member 110 may also be varied as desired in a particular application in order to accommodate a relatively larger or smaller current transformer in the compartment 150 which results around the lower terminal of the circuit breaker 10 as disclosed.

The apparatus embodying the teachings of the invention has several advantages. For example, a circuit interrupter or circuit breaker having an improved insulating support structure as described where a current transformer is to be mounted or combined with a circuit interrupter as disclosed on one of the terminals thereof, is relatively more compact than circuit interrupters employing known insulating support structures of the same general type. in addition, where the circuit breaker 10 is normally disposed in an associated switchgear cell or housing, the associated cell or housing may also be more compact due to the reduction in the relative size of the circuit breaker 10. ln other words, the circuit interrupter construc tion as disclosed reduces the length or size of the required upper and lower terminals substantially to a minimum where a current transformer is to be mounted or supported on one of the tenninals of the circuit interrupter.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What I claim is:

1. An electric circuit interrupter comprising an electrically insulating base member having first and second generally planar portions interconnected by an intermediate planar portion disposed generally perpendicular to said first and second planar portions, said first and second planar portions being generally parallel to each other and offset from one another by a predetermined spacing, a stationary contact assembly mounted on said first planar portion at one side of said base member and including first terminal means, said first'terminal means extending through an opening in said first planar portion and projecting away from said first planar portion in a direction generally perpendicular to said first planar portion a predetermined distance from said first planar portion, an electrically conducting hinge support member mounted on said second planar portion at the same side of said base member as said stationary contact assembly and having associated therewith second terminal means, said second terminal means extending through an opening in said second planar portion and projecting in the same direction away from said second planar portion as said first'terminal means for a' distance substantially equal to the sum of said predetermined spacing and said predetermined distance and a switch arm having movable contacts thereon pivotally supported on said hinge support member for movement between a first position in which said movable contacts engage said stationary contact assembly and a second position, the predetermined spacing between said first and second planar portions being sufficient to permit the planar portions, said mounting of a current transformer between said second planar portion and the end of saidsecond terminal means away from said second planar portion.

2. An electric circuit interrupter comprising an electrically insulating base member having first and second generally planar portions interconnected by an intermediate planar portion disposed generally perpendicular to said first and second lrst and second planar portions being generally parallel to each other and offset from one another by a predetermined spacing, a stationary contact assembly mounted on said first planar portion at one side of said base member and including first terminal means, said first terminal means extending through an opening in said first planar portion and projecting away from said first planar portion in a direction generally perpendicular to said first planar portion a predetermined distance from said first planar portion, an electrically conducting hinge support member mounted on said second planar portion at the same side of said base member as said stationary contact assembly and having associated therewith second terminal means, said second terminal means extending through an openingin said second planar portion and projecting in the same direction away from said second planar portion as said first terminal means for a distance substantially equal to the sum of said predetermined spacing and said predetermined distance, a switch arm having movable contacts thereon pivotally supported on said hinge support member for movement between a first position in which said movable contacts engage said stationary contact assembly and a second position and a current transformer mounted on said second terminal means between said second planar portion and the end of said second terminal means away from said second planar portion.

3. The combination as claimed in claim 1 wherein said insulating base member includes a pair of sidewall portions disposed at the opposite sides of said first and second planar portions generally perpendicular to said first and second planar portions.

4. The combination as claimed in claim 1 wherein said insulating base member includes a pair of sidewall portions disposed at the opposite sides of said first and second planar portions and projecting away from said first and second planar portions in both directions generally perpendicular to said first and second planar portions.

5. The combination as claimed in claim 3 wherein a current transformer is mounted on the second terminal means between the second planar portion and the end of said second terminal means away from said second planar portion and disposed between said sidewall portions.

6. The combination as claimed in claim 4 wherein a current transformer is mounted on the second terminal means between the second planar portion and the end of said second terminal means away from said second planar portion and disposed between said sidewall portions.

7. The combination as claimed in claim 2 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions.

8. The combination as claimed in claim 5 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions.

9. The combination as claimed in claim 6 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions. 

1. An electric circuit interrupter comprising an electrically insulating base member having first and second generally planar portions interconnected by an intermediate planar portion disposed generally perpendicular to said first and second planar portions, said first and second planar portions being generally parallel to each other and offset from one another by a predetermined spacing, a stationary contact assembly mounted on said first planar portion at one side of said base member and including first terminal means, said first terminal means extending through an opening in said first planar portion and projecting away from said first planar portion in a direction generally perpendicular to said first planar portion a predetermined distance from said first planar portion, an electrically conducting hinge support member mounted on said second planar portion at the same side of said base member as said stationary contact assembly and having associated therewith second terminal means, said second terminal means extending through an opening in said second planar portion and projecting in the same direction away from said second planar portion as said first terminal means for a distance substantially equal to the sum of said predetermined spacing and said predetermined distance and a switch arm having movable contacts thereon pivotally supported on said hinge support member for movement between a first position in which said movable contacts engage said stationary contact assembly and a second position, the predetermined spacing between said first and second planar portions being sufficient to permit the mounting of a current transformer between said second planar portion and the end of said second terminal means away from said second planar portion.
 2. An electric circuit interrupter comprising an electrically insulating base member having first and second generally planar portions interconnected by an intermediate planar portion disposed generally perpendicular to said first and second planar portions, said first and second planar portions being generally parallel to each other and offset from one another by a predetermined spacing, a stationary contact assembly mounted on said first planar portion at one side of said base member and including first terminal means, said first terminal means extending through an opening in said first planar portion and projecting away from said first planar portion in a direction generally perpendicular to said first planar portion a predetermined distance from said first planar portion, an electrically conducting hinge support member mounted on said second planar portion at the same side of said base member as said stationary contact assembly and having associated therewith second terminal means, said second terminal means extending through An opening in said second planar portion and projecting in the same direction away from said second planar portion as said first terminal means for a distance substantially equal to the sum of said predetermined spacing and said predetermined distance, a switch arm having movable contacts thereon pivotally supported on said hinge support member for movement between a first position in which said movable contacts engage said stationary contact assembly and a second position and a current transformer mounted on said second terminal means between said second planar portion and the end of said second terminal means away from said second planar portion.
 3. The combination as claimed in claim 1 wherein said insulating base member includes a pair of sidewall portions disposed at the opposite sides of said first and second planar portions generally perpendicular to said first and second planar portions.
 4. The combination as claimed in claim 1 wherein said insulating base member includes a pair of sidewall portions disposed at the opposite sides of said first and second planar portions and projecting away from said first and second planar portions in both directions generally perpendicular to said first and second planar portions.
 5. The combination as claimed in claim 3 wherein a current transformer is mounted on the second terminal means between the second planar portion and the end of said second terminal means away from said second planar portion and disposed between said sidewall portions.
 6. The combination as claimed in claim 4 wherein a current transformer is mounted on the second terminal means between the second planar portion and the end of said second terminal means away from said second planar portion and disposed between said sidewall portions.
 7. The combination as claimed in claim 2 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions.
 8. The combination as claimed in claim 5 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions.
 9. The combination as claimed in claim 6 wherein at least a portion of said current transformer is disposed in said predetermined spacing between said first and second planar portions. 